Preliminary studies on the optimization of countermeasures for agricultural areas

The assessment of remediation measures for rural areas is more complex than that for urban ones, due to the influence of large number of variables associated with climate, diet, farming practices and the type of soil. Thus, it is not possible to perform generic studies applicable to all types of area. Specific studies and surveys should be made in the areas most likely to contamination from a nuclear accident. Preliminary studies demonstrated that the different soil types in Brazil is more relevant to the ingestion dose than the regional differences in diets. Other studies have described the prioritization of areas and products for detailed survey on soil types and remediation procedures, for an accident at the NPP in Angra dos Reis, based on radiological and economic aspects. The most relevant product was milk, due to both its relevance to the intake and the loss of income for the counties. The contribution of milk to dose depends on the season of the year when the accident occurs, mainly due to the relative contribution of other items of the diet. The timing of the application of the countermeasure has an important effect on the dose reduction that can be achieved. For I-131, protective measures must be considered within the emergency phase in order to be effective. The main action on reducing ingestion doses is the removal of food items from diet, while providing clean food to the population

Priority of areas for agricultural radiovulnerability mapping

The methodology for classifying areas according to soil properties for the vulnerability to a 137Cs contamination is of high importance to the preparedness related to nuclear and/or radiological accidents that lead to release of radionuclides to the environment with the consequent contamination of agricultural areas. The priority of research for agricultural areas should then focus on the surrounding areas of nuclear power plant that have higher probability of public exposure through the ingestion pathway. The objective of this work was to create a rank order for priority of areas to be mapped based on EMBRAPA database on soil properties. The 16 municipalities previously selected to define parameters for dose assessment simulations related to the Brazilian Nuclear Power Plants, located in the district of Angra dos Reis, Rio de Janeiro, have been investigated in order to create this rank order to direct the research on radiovulnerability mapping, considering their relevance to public exposure based on their agricultural productivity. The two aspects selected in this study account for the maximum loss of income and to the collective doses that can be averted due to the banning of agricultural INAC 2013, Recife, PE, Brazil. products. These quantities are inputs to optimization analysis. The priority defined shall then guide research on both the adequate values for the transfer factors and on the agricultural countermeasures suitable to each area according to the cause(s) of their vulnerability and their typical agricultural crops

Multi-criteria model to support decision-making for the remediation of urban areas

Under the environmental modeling Project of radioecology research area of IRD (CNEN), several tools have been developed to support post-emergency activities. Currently, a multi-criteria model is in development with the aim of supporting decision-making processes under the radiological protection point of view. At this stage, we are focusing on the decontamination of urban areas. The model includes five calculation modules: (i) averted doses to the public due to remediation procedures; (ii) occupational exposure of remediation workers; (iii) properties of the wastes generated by a remediation procedure; (iv) classification of each procedure for a specific urban scenario based on previously calculated quantities; and, (v) multi-criteria rank calculation. The classification of procedures is based on two types of criteria previously defined, both also included as input data of the model. The first type, called Subjective Criteria, is based on experts’ opinions collected through questionnaires. The second type, called Technical Criteria, is calculated according to the outputs of the three first modules of the program. The output of the model is a rank order list indicating the priority of procedures to use for each different type of urban environment. The use of results based on criteria and methods developed previously to the occurrence of a contamination event intends not only to provide an input to decision-making processes but also to improve public confidence on authorities responsible for the remediation decisions

Sorption study of u+6 in brazilian soils

The uranium mining is one of the main activities of the nuclear fuel cycle that can contribute to the increased exposure to radioactive materials and is one of the main routes of contamination of soil by natural radionuclides. This study investigated the sorption of uranium in brazilian soils, through sorption isotherms performed in batch. In this study, two types of soils were selected: Ferralsols Red and Nitosol. The adjustment of the experimental data to the kinetic models were evaluated by two approaches: the traditional, based on the coefficient of determination (R2); and the theoretical and informative, based on Corrected Akaike Information Criteria (AICC). The coefficient of determination (R2), revealed that, although empirical, both the kinetic model, Freundlich and Langmuir, describes satisfactorily the experimental data, showing R2 values higher than 0.9, while the partition constant model was not suitable for describe these sorption data. The AICC model analysis showed that the Langmuir model fit the U sorption curve well for Ferralsols Red, while the Freundlich model fits better to Nitosol. This study has highlighted the role of organic matter on the sorption of uranium in highly weathered soils, rich in oxyhydroxides and low activity clays. The Kd values reported in this study differ from those recommended by the United States Environmental Protection Agency, therefore must be considered as reference values for highly weathered soils, since it refers to Brazilian pedoenvironmental conditions. The low Kd values obtained in this study allowed us to evaluate the high vulnerability of highly weathered soils to uranium contamination

Evaluation of the mobility of 123CS in soil profiles of the pantanal region

Radioactive pollutants can cause impact on the environmental quality of soils and represent a risk to human health. Radioecological studies have shown that soils with low pH, low organic matter content and low fertility are more vulnerable to contamination by 137Cs, since the transfer to plants is high. In this study, some surface horizons of soils from Jaraguari, situated at Brazilian Pantanal were assessed in order to map their vulnerability to contamination by 137Cs. It was also proposed some mitigation measures adapted to the regional scenario in order to optimize radiological protection for rural areas. A conceptual model established to detect the vulnerability of radioactively contaminated soils was applied for soils located in the municipality of Jaraguari (Mato Grosso do Sul). This conceptual model was established based on the relationship between reference values of the soil-to-plant transfer factor (TF) for 137Cs and critical pedological parameters for each radiovulnerability category (pH, CTC and exchangeable K). The application of this conceptual model to a soil databank using Geographic Information System (GIS) tools generated vulnerability soils maps. This result identified that most of Pantanal soils presented very low radiovulnerability, but it was possible to detect some small areas presenting extreme radiovulnerability. It was possible to conclude that these small areas is not indicated for activities that presents a potential risk for 137Cs contamination and also it must receive priority actions for remediation in the case of accident, since a superficial contamination with 137Cs in these areas can lead to a contamination of subsoil and to a significant spread of contamination via groundwater

Geoquímica de radionuclídeos naturais em solos de áreas circunvizinhas a uma Unidade de Mineração e Atividade de Urânio Geochemistry of natural radionuclide in soils surrounding a Mining and Plant Uranium Concentration

Os impactos ambientais advindos da exploração e do beneficiamento de U são, em grande parte, idênticos àqueles causados por atividades minero-extrativistas em geral. Este trabalho teve o objetivo de determinar a partição geoquímica dos radionuclídeos naturais 238U, 226Ra e 210Pb em áreas circunvizinhas à Unidade de Mineração e Atividade de Urânio (URA) das Indústrias Nucleares do Brasil S.A., localizada na Província Uranífera de Lagoa Real, no município de Caetité, na região sudoeste do Estado da Bahia. Foram coletadas amostras de solo em cinco áreas circunvizinhas à URA, representando as principais classes de solos da região, na profundidade de 0-20 cm. Nas cinco áreas, foram determinados o teor de atividade total e o fracionamento geoquímico nas frações: F1 - levemente ácida, F2 - reduzível, F3 - oxidável, F4 - alcalina e F5 - residual. As atividades totais médias foram, em Bq kg-1 de solo, de 50 para 238U, 51 para 226Ra e 159 para 210Pb. Os extraídos na fase potencialmente biodisponível (F1) foram: 11 % para 238U, 13 % para 226Ra e 3 % para 210Pb. O 238U apresentou maior biodisponibilidade nos solos mais ácidos e maior afinidade pelos óxidos de Fe, o que não ocorreu para o 226Ra, tendo este apresentado a maior biodisponibilidade. O 210Pb apresentouse predominantemente associado a F5. As percentagens elevadas de 238U, 226Ra e 210Pb na fração geoquímica F5 indicam que as atividades observadas nos cinco solos estão, predominantemente, associadas ao material que deu origem a esses solos, e não a um processo de contaminação artificial em função da atividade da URA.<br>The environmental impacts resulting from uranium exploration and processing are to a great extent identical to those caused by extractive mining activities in general. This study aimed to determine the geochemical partitioning of the natural radionuclides 238U, 226Ra and 210Pb in areas surrounding the Uranium Mining and Concentration Plant (URA) of the Brazilian Nuclear Industries S.A., in the uranium deposit region of Lagoa Real, in Caetité, southwestern Bahia state. Representative soil samples of the main regional soil classes were collected from the layer 0-20 cm, in five areas around the URA. The level of total activity and geochemical fractionation (F1slightly acidic, F2 reducible, F3 oxidisable, F4 alkaline, and F5 residual) were determined for the five areas. The average total radioactivity levels were, in Bq kg-1 soil: 50 for 238U, 51 for 226Ra, and 159 for 210Pb. During the potentially bioavailable phase (F1) 11 % were extracted for 238U, 13 % for 226Ra and 3 % for 210Pb. The bioavailability of 238U was higher in more acidic soils and the affinity for iron oxides was greater, unlike in the case of 226Ra, with the greatest bioavailability. 210Pb was predominantly associated with F5. The high percentage of 238U, 226Ra and 210Pb in the geochemical fraction F5 indicates that the concentrations observed in the five soils are predominantly associated to the parent material of these soils, rather than to an artificial contamination caused by the URA activity